Water purification involves the process of filtering undesirable contaminants, biological agents, solids, and gases from water for a variety of purposes. Companies that specialize in water filtration aim to create a water source suitable for consumption. Medical, pharmacological, and chemical industries apply water filtration techniques to meet the standards of regulatory bodies. Water purification processes may include filtration, sedimentation, and distillation. The biological processes of water purification may involve biologically active carbon filters. In addition, the chemical processes of water purification involves flocculation, chlorination, and electromagnetic radiation.

What is Water Purification?

According to the World Health Organization (WHO), an estimated one million people lack an adequate source of pure drinking water. Water purification processes aim to reduce the overall concentration of particulates in a water source, including parasites, bacteria, algae, fungi, viruses, and free radicals. Some of these particulates can not be seen by the naked eye. Simple water filtration procedures, such as boiling, iodine, and activated carbon filters, fail to remove all of the contaminants present in the water. Therefore, water filtration processes aimed to produce quality drinking water must meet the standards set by governmental and international regulatory bodies. Even water retrieved from natural bodies of water, such as springs and wells, must undergo rigorous testing before it passes as safe drinking water. Water filtration processing centers may incorporate microbiological and chemical analysis to determine the appropriate purification method.

Sources of Water

Water filtration centers retrieve contaminated water from five different sources, including groundwater, upland lakes and reservoirs, rivers, canals, water generators, rainwater harvesters, fog collectors, and the sea. Many of these filtration centers will pump groundwater after it rains. The soil and sedimentary layers naturally filter groundwater from its contaminants; however, water treatment centers will add chlorine as a secondary measure. Water filtration centers will often target artesian springs, boreholes, and wells. Water treatment facilities extract water from upland reservoirs and lakes, where bacteria and pathogen levels remain unusually low. River and canals offer an easily accessible medium for water; however, it usually contains high levels of bacteria, algae, suspended solids, and other dissolved contaminates. Some water treatment facilities produce their own water through atmospheric generation, a new technology that provides quality drinking water by extracting it from the air. Rainwater harvesting and fog collection involves the same process, except in areas where it rains or fogs almost continuously. Desalination involves the process of extracting the sodium content from seawater to make it suitable for human consumption. Lastly, water treatment facilities may extract water from freshwater bodies and then filter it of any protozoa, algae, fungus, bacteria, and other contaminants.

Treatment Process

Water filtration plants may employ a variety of processes to purify contaminated water into suitable water meant for human consumption. In general, the treatment process involves extracting the water from a natural source by pumping, containing, screening, chlorinating, and storing it safely without endangering any wildlife. After the initial preparation phase, each water filtration center will attempt to adjust the pH level in the water by adding lime, soda ash, or sodium hydroxide, especially if the pH ranks lower than 7. Once the water filtration center achieves a desirable pH level, it may add coagulation chemicals that remove suspended solids within the water, such as clay, silt, algae, bacteria, protozoa, viruses, and other forms of organic matter. Next, the water exits the flocculation basin and then enters the sedimentation clarifier, a large tank with low flowing velocities that allow the floc to settle at the bottom of the basin. A layer of sludge begins to form at the bottom of the clarifier, which causes a demand for its removal and disposal. If the removed particles fail to settle out of the solution, then the water treatment facilities may turn to dissolved air flotation before starting the filtration process. Most water filtration facilities use a rapid sand filter to move water vertically through activated carbon, where the top layer removes all organic compounds and all existing contaminants. Slow sand filters water very slowly from all undesirable compounds, organic material, and biological agents. Membrane filters purify drinking water and sewage. In addition, water treatment facilities may use ultrafiltration membranes to remove dissolved substances without incorporating the use of coagulant chemicals. Other filtration methods include ion exchange, precipitative softening, and electrodeionization. After filtering out the contaminants, the water treatment facilities will disinfect the water using chlorine, chloramine, ozone, electromagnetic radiation, and other portable methods. Other water treatment methods may include water fluoridation, conditioning, plumbosolvency, radium removal, and fluoride removal.

Safety and Controversies

Water filtration facilities have drawn a negative light to themselves in recent years, mainly centered around its disinfectant agents. Many municipalities incorporate chloramine, instead of chlorine to disinfect water; however, chloramine has a reputation for dissolve the protective lining of service lines. This results in the harmful exposure to lead, and other heavy metals. Critics also assert that distilling water removes all of the necessary minerals from within it. Studies have revealed that demineralized water aids in the development of nutritional deficiencies. In addition, demineralized water may increase the chance of heavy metal toxicity. Proponents of demineralized water assert that the problem stems from nutritionally devoid foods. However, mineralized water with heavy concentrations of calcium may be defined as "hard water," an undrinkable water source that may result if the formation of kidney stones, gallstones, urinary stones, and other problems if ingested on a regular basis.